Substrate processing method and apparatus

ABSTRACT

There is provided a substrate processing method which, even when a material having a low mechanical strength is employed as an interlayer dielectric, can produce a semiconductor device having a multi-layer interconnect structure of fine interconnects in higher yield. A substrate processing method according to the present invention includes the steps of: providing a substrate having interconnect recesses formed in a surface; forming a metal film on the surface of the substrate by plating to embed the metal film in the interconnect recesses; removing the metal film formed in an ineffective region of the substrate and an extra metal film formed in an effective region of the substrate; and flattening the surface of the substrate after the removal of the metal film by chemical-mechanical polishing.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a substrate processing method and apparatus, and more particularly to a substrate processing method and apparatus which is useful, for example, in the fields of LSI, displays and magnetic heads, and in the field of chip mounting thereof, for forming a metal film (interconnect material), such as a copper film, by plating on the surface of a substrate having fine interconnect recesses (interconnect patterns) formed in a surface and removing an extra metal film, thereby forming metal interconnects of a submicron to micron size.

[0003] 2. Description of the Related Art

[0004] In recent years, instead of using aluminum or aluminum alloys as an interconnect material for forming electrical interconnects on a semiconductor substrate, there is an eminent movement toward using copper (Cu) which has a low electric resistivity and high electromigration resistance. It is generally difficult with copper to form interconnects by anisotropic etching as practiced with aluminum. Accordingly, copper interconnects are generally formed by a so-called copper damascene technique which comprises embedding of copper in fine recesses formed in a surface of a substrate. Known methods for forming such copper interconnects include CVD, sputtering and plating. According to any such method, a copper film is formed on almost the entire surface of a substrate, followed by removal of unnecessary copper by chemical-mechanical polishing (CMP).

[0005]FIGS. 1A through 1C illustrate, in sequence of process steps, a process for producing a substrate W having such copper interconnects, and FIG. 2 is a flow chart of the process. First, as shown in FIG. 1A, an insulating film (interlayer dielectric) 2, for example, an oxide film of SiO₂ or a film of a low-k material, is deposited on a conductive layer 1 a in which semiconductor devices are formed and which is formed on a semiconductor base 1. Fine interconnect recesses, such as fine holes (via holes) 3 and interconnect trenches 4, are formed in the insulating film 2 by the lithography/etching technique. Thereafter, a barrier layer 5 of TaN or the like is formed on the entire surface, and a seed layer 7, serving as an electric feeding layer in electroplating, is formed on the barrier layer 5. A substrate W having fine interconnect recesses formed in a surface is thus prepared.

[0006] Then, as shown in FIG. 1B, copper plating of the surface of the substrate W is carried out to fill the fine holes 3 and the interconnect trenches 4 with copper and, at the same time, deposit a copper film 6 on the insulating film 2 (step 1). At this stage, the copper film 6 is deposited on the entire surface of the substrate w including, besides the device-formation-region, the edge (bevel) portion which is an ineffective region. Further, a copper film can inevitably be formed on a back surface of the substrate W. Accordingly, the copper film deposited in the ineffective region, such as the edge (bevel) portion, of the substrate is removed, for example by etching, followed by cleaning and, if necessary, the back surface of the substrate is also cleaned (step 2). Further, according to necessity, the substrate W is subjected to annealing (heating) or infrared irradiation to grow and stabilize the metal crystals of the copper film 6 (step 3).

[0007] Next, an extra or unnecessary copper film 6 and the barrier layer 5 on the insulating film 2 are removed by chemical-mechanical polishing (CMP) so as to make the surface of the copper film 6, filled in the fine holes 3 and the interconnect trenches 4, substantially flush with the surface of the insulating film 2. Interconnects, which are formed of the copper film 6, as shown in FIG. 1C, are thus formed (step 4). The front and back surfaces of the substrate, having the interconnects of copper film 6, are cleaned by using a combined chemical and physical means, for example a combination of a chemical and scrubbing, and rinsed (cleaned) with pure water, followed by spin-drying (step 5). The substrate after drying is then sent to the next process.

[0008] The above-described crystal stabilization processing is generally carried out by heating the substrate in an inert gas atmosphere. In some cases, however, it is effective to allow the substrate to stand at room temperature to effect spontaneous annealing (step 3), as shown in FIG. 3.

[0009]FIG. 4 schematically shows a conventional common plating apparatus including a plating unit for carrying out the above-described plating, and a removal unit, for example comprised of a bevel etching/back surface cleaning unit, for carrying out the above-described removal of a metal film (copper film) in the ineffective region of a substrate and cleaning of the substrate. The plating apparatus 10 includes a rectangular apparatus frame 14 and transport boxes 12, detachably mounted to the apparatus frame 14, each housing substrates, e.g. substrates W having a seed layer 7, shown in FIG. 1A. Inside the apparatus frame 14 are disposed a stage 16, four plating units 18, two bevel etching/back surface cleaning units (removal units) 20, and two transport robots 22, 24 as transport devices.

[0010] According to the plating apparatus 10, substrates, e.g. the substrates W having a seed layer 7, are carried one by one by the transport robot 22 from the transport box 12 into the apparatus frame 14, and the substrate is transported to one of the plating units 18, where the substrate is plated. The substrate after plating is transported to one of the bevel etching/back surface cleaning units 20, where removal by etching of e.g. a copper film deposited in the ineffective region of the substrate and the subsequent cleaning and, according to necessity, cleaning of the back surface of the substrate are carried out, followed by drying. Thereafter, the substrate is returned by the transport robot 22 to the original position in the transport box 12.

[0011]FIG. 5 schematically shows a conventional common annealing apparatus (crystal stabilization apparatus) having an annealing unit (crystal stabilization unit) for carrying out crystal stabilization processing of a metal film by the above-described annealing (heating). The annealing apparatus 26 includes a rectangular apparatus frame 28 and transport boxes 12, detachably mounted to the apparatus frame 28, each housing substrates, e.g. the substrates having a copper film 6 which has been deposited by the above plating apparatus 10, such as shown in FIG. 1B. Inside the apparatus frame 28 are disposed two annealing units 30 and a transport robot 32 as a transport device.

[0012] According to the annealing apparatus 26, the substrates after plating, for example, are carried one by one by the transport robot 32 from the transport box 12 into the apparatus frame 28, and the substrate is transported to one of the annealing units 30, where the substrate is subjected to annealing. The substrate after annealing is returned by the transport robot 32 to the original position in the transport box 12.

[0013]FIG. 6 schematically shows a conventional common CMP apparatus having a CMP unit for carrying out the above-described chemical-mechanical polishing (CMP). The CMP apparatus 34 includes a rectangular apparatus frame 36 and transport boxes 12, detachably mounted to the apparatus frame 36, each housing e.g. the substrates which have been annealed in the above annealing apparatus 26. Inside the apparatus frame 36 are disposed two CMP units 46, each including a top ring 38, a turntable (polishing table) 40, a dresser 42 and a loader 44, for polishing a substrate by pressing the substrate held by the top ring 38 against the polishing surface (upper surface) of the turntable 40 while moving the substrate and the turntable 40 relative to each other. There are also disposed two stages 48, two scrub cleaning units 50 for carrying out scrub cleaning, two cleaning/drying units 52 for carrying out rinsing (cleaning) with pure water and spin-drying, and three transport robots 54, 56, 58 as transport devices inside the apparatus frame 36.

[0014] According to the CMP apparatus 34, the substrates after annealing are carried one by one by the transport robot 54 from the transport box 12 into the apparatus frame 36, and the substrate is transported to one of the CMP units 46, where the substrate is subjected to chemical-mechanical polishing (CMP). The substrate after CMP is transported to one of the scrub cleaning units 50 for scrub cleaning of the substrate, and the cleaned substrate is transported to one of the cleaning/drying units 52 for rinsing with pure water and spin-drying of the substrate. Thereafter, the substrate is returned by the transport robot 54 to the original position in the transport box 12.

[0015] A composite apparatus 60 which combines the above-described plating apparatus 10 and annealing apparatus 26, as shown in FIG. 7, is known. As shown in FIG. 7, the annealing unit 30 is provided beside the above-described plating apparatus 10 and they communicate with each other through a passage 62, so that after plating and the subsequent bevel etching/back surface cleaning of a substrate, annealing of the substrate can be carried out successively.

[0016] For the formation of metal interconnects in e.g. an LSI, it is a conventional practice to employ the above-described plating apparatus 10, annealing apparatus 26, CMP apparatus 34, etc. in a proper combination. With the progress toward finer metal interconnects and the emergence of new interlayer dielectric materials, many unexpected technical problems have arisen. Such technical problems have not surfaced in conventional interconnect formation processes which use, as interlayer dielectric materials, the existing materials such as SiO₂, SiOF, SiOC, SiLK, etc. The following is a description of the technical problems.

[0017] Porous materials (porous low-k materials), which have a lower dielectric constant k than the conventional insulating materials, are attracting attention as promising next-generation interlayer dielectric materials. Such materials, because of their internal porous structure, generally have lower mechanical strength and thus are weaker than the conventional interlayer dielectric materials. The use of such a porous material can cause peel-off or separation of the interlayer dielectric or copper interconnects during chemical-mechanical polishing (CMP), leading to an interconnect breaking or short circuit. Many factors may be involved in the problems or drawbacks, such as a shortage of the mechanical strength of the interlayer dielectric itself, poor adhesion at the interface between the insulating film and a different material, interfacial peeling cause by a difference in expansion/contraction upon a thermal change between different materials, for example, a porous low-k material and a metal, etc.

[0018] In order to solve or minimize the problems, it is most desirable to provide a low-k material with enhanced strength. Other approaches are directed to technical improvements, such as lowering of the stress applied to a substrate in a chemical-mechanical polishing process (e.g. low-load polishing), reduction of the expansion/contraction difference between materials in a metal crystal stabilization process, minimization of a thickness of a plated film in a plating process, reduction of a level difference after plating, etc. These approaches, however, have their own difficult problems that would take a long time to solve.

SUMMARY OF THE INVENTION

[0019] The present invention has been made in view of the above situation in the related art. It is therefore an object of the present invention to provide a substrate processing method and apparatus which, even when a material having a low mechanical strength is employed as an interlayer dielectric, can produce a semiconductor device having a multi-layer interconnect structure of fine interconnects in higher yield.

[0020] In order to achieve the above object, the present invention provides a substrate processing method comprising the steps of: providing a substrate having interconnect recesses formed in a surface; forming a metal film on the surface of the substrate by plating to embed the metal film in the interconnect recesses; removing the metal film formed in an ineffective region of the substrate and an extra metal film formed in an effective region of the substrate; and flattening the surface of the substrate after the removal of the metal film by chemical-mechanical polishing.

[0021] According to this method, in advance of chemical-mechanical polishing which is likely to cause damage to a substrate, a metal film formed in excess in the effective region of the substrate is made thin. This reduces a stress to interconnects due to expansion/contraction difference. Further, the polishing time itself can be minimized. Accordingly, peel-off or separation of an interlayer dielectric and interconnects can be prevented even when a material having a low mechanical strength is employed for the interlayer dielectric.

[0022] The present invention also provides a substrate processing method comprising the steps of: providing a substrate having interconnect recesses formed in a surface; forming a metal film on the surface of the substrate by plating to embed the metal film in the interconnect recesses; removing the metal film formed in an ineffective region of the substrate and an extra metal film formed in an effective region of the substrate; cleaning the substrate after the removal of the metal film; subjecting the substrate after the cleaning to crystal stabilization processing to stabilize the metal crystals of the metal film; and flattening the surface of the substrate after the crystal stabilization processing by chemical-mechanical polishing.

[0023] This method includes the step of stabilizing the metal crystals of themetal film, for example, by annealing. According to this method, in advance of the crystal stabilization processing (annealing) step, the metal film formed in excess in the effective region of the substrate is made thin, thereby reducing a stress to interconnects due to expansion/contraction difference. Further, the time required for the stabilization of metal crystals can be minimized.

[0024] In a preferred embodiment of the present invention, the removal of the extra metal film formed in the effective region of the substrate is a partial removal for removing part of the extra metal film, and the thickness of the remaining metal film is measured to control the removal amount of the metal film.

[0025] By measuring the thickness of the metal film remaining in the effective region of the substrate during the metal film removal step and feeding back the measured thickness, the removal amount of the metal film can be controlled in situ.

[0026] The metal film may be a copper, copper alloy, silver or silver alloy film.

[0027] The present invention may be used primarily in the field of LSI. In that field, copper, a copper alloy, silver or a silver alloy is primarily used as an interconnect material for fine interconnects. The metal film, of course, is not limited to these metals.

[0028] In a preferred embodiment of the present invention, the removal of the extra metal film formed in the effective region of the substrate is carried out by chemical etching, electrolytic etching or composite electrolytic polishing.

[0029] Chemical agents commonly used in chemical etching include hydrogen peroxide, ozone, etc. as oxidizing agents and sulfuric acid, hydrochloric acid, hydrofluoric acid and other chelating agents as metal removal agents. It is possible to oxidize the surface of a metal film with ultraviolet rays. Electrolytic etching is carried out by utilizing a metal film formed on a substrate as an anode, and immersing the metal film in an electrolytic solution such that the metal film faces an anode disposed in the electrolytic solution and passing an electric current between the anode and the cathode, thereby oxidizing and ionizing and thereby removing the metal film. Composite electrolytic polishing is a polishing method which comprises oxidizing and chelating (complexing) the surface of a metal film in an electrolytic solution to thereby make the metal film surface weak or fragile, and scrub-removing the fragile metal film by bringing the metal film into mechanical contact with a contact member. For the chelation of metal film, a chelating agent is added to the electrolytic solution. The electrolytic solution may be exemplified by an electrolytic solution containing an electrolyte, such as copper sulfate or ammonium sulfate. It is possible to add abrasive grains or a slurry to the electrolytic solution to enhance the mechanical polishing action.

[0030] The removal of the extra metal film formed in the effective region of the substrate may be carried out by chemical-mechanical polishing.

[0031] The present invention provides a substrate processing apparatus comprising: a plating unit for forming a metal film on a surface of a substrate having interconnect recesses formed in a surface to embed the metal film in the interconnect recesses; a partial removal unit for removing part of an extra metal film formed in an effective region of the substrate; and a transport device for transporting the substrate between the units.

[0032] In a preferred embodiment of the present invention, the partial removal unit is a chemical etching unit, an electrolytic etching unit or a composite electrolytic polishing unit. The partial removal unit may be a chemical-mechanical polishing unit.

[0033] The substrate processing apparatus may further comprise a removal unit for removing the metal film formed in an ineffective region of the substrate.

[0034] The substrate processing apparatus may further comprise a crystal stabilization unit for stabilizing the metal crystals of the metal film remaining on the substrate after the partial removal of the extra metal film in the partial removal unit.

[0035] The substrate processing apparatus may further comprise a cleaning unit for cleaning the substrate.

[0036] The substrate processing apparatus may further comprise a chemical-mechanical polishing unit for removing the extra metal film remaining on the substrate after the partial removal of the extra metal film in the partial removal unit and flattening the surface of the substrate.

[0037] The substrate processing apparatus may further comprise a film thickness measuring section for measuring the thickness of the metal film remaining on the substrate after the partial removal of the extra metal film in the partial removal unit, and controlling the partial removal unit based on the results of the measuring.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038]FIGS. 1A through 1C are diagrams illustrating, in sequence of process steps, a conventional process for forming copper interconnects;

[0039]FIG. 2 is a flow chart of a conventional method for forming the copper interconnects shown in FIGS. 1A through 1C;

[0040]FIG. 3 is a flow chart of another conventional method for forming the copper interconnects shown in FIGS. 1A through 1C;

[0041]FIG. 4 is a layout plan of a conventional plating apparatus;

[0042]FIG. 5 is a layout plan of a conventional annealing apparatus;

[0043]FIG. 6 is a layout plan of a conventional CMP apparatus;

[0044]FIG. 7 is a layout plan of a conventional composite apparatus which combines a plating apparatus and an annealing apparatus;

[0045]FIGS. 8A through 8D illustrate, in sequence of process steps, the formation of copper interconnects by a substrate processing method according to the present invention;

[0046]FIG. 9 is a flow chart of a substrate processing method according to an embodiment of the present invention (first method);

[0047]FIG. 10 is a flow chart showing a variation of the first method shown in FIG. 9;

[0048]FIG. 11 is a layout plan of a substrate processing apparatus according to an embodiment of the present invention, which is suited for carrying out the first method;

[0049]FIG. 12 is a layout plan of a substrate processing apparatus according to another embodiment of the present invention, which is suited for carrying out the first method;

[0050]FIG. 13 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the first method;

[0051]FIG. 14 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the first method;

[0052]FIG. 15 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the first method;

[0053]FIG. 16 is a flow chart of a substrate processing method according to another embodiment of the present invention (second method);

[0054]FIG. 17 is a flow chart showing a variation of the second method shown in FIG. 16;

[0055]FIG. 18 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the second method;

[0056]FIG. 19 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the second method;

[0057]FIG. 20 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the second method;

[0058]FIG. 21 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the second method;

[0059]FIG. 22 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the second method;

[0060]FIG. 23 is a flow chart of a substrate processing method according to yet another embodiment of the present invention (third method);

[0061]FIG. 24 is a flow chart showing a variation of the third method shown in FIG. 23;

[0062]FIG. 25 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the third method;

[0063]FIG. 26 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the third method;

[0064]FIG. 27 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the third method;

[0065]FIG. 28 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the third method; and

[0066]FIG. 29 is a layout plan of a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the third method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] Preferred embodiments of the present invention will now be described with reference to the drawings. The following description illustrates, by way of example, the case of forming copper interconnects on the surface of a substrate.

[0068]FIGS. 8A through 8D illustrate, in sequence of process steps, the formation of copper interconnects by a substrate processing method according to the present invention, and FIG. 9 shows a flow chart of a substrate processing method according to an embodiment of the present invention (first method). According to this method, as shown in FIG. 8A, an insulating film (interlayer dielectric) 2, for example, an oxide film of SiO₂ or a film of a low-k material, is deposited on a conductive layer la in which semiconductor devices are formed and which is formed on a semiconductor base 1. Fine interconnect recesses, such as fine holes (via holes) 3 and interconnect trenches 4, are formed in the insulating film 2 by the lithography/etching technique. Thereafter, a barrier layer 5 of TaN or the like is formed on the entire surface, and a seed layer 7, serving as an electric feeding layer in electroplating, is formed on the barrier layer 5. A substrate W having fine interconnect recesses formed in a surface is thus prepared.

[0069] Then, as shown in FIG. 8B, copper plating of the surface of the substrate W is carried out to fill the fine holes 3 and the interconnect trenches 4 with copper and, at the same time, deposit a copper film 6 on the insulating film 2 (step 1). At this stage, the copper film 6 is deposited on the entire surface of the substrate w including, besides the device-formation-region, the edge (bevel) portion which is an ineffective region. Further, a copper film can inevitably be formed on a back surface of the substrate W. Accordingly, the copper film deposited in the ineffective region, such as the edge (bevel) portion, of the substrate is removed, for example by etching, followed by cleaning and, if necessary, the back surface of the substrate is also cleaned (step 2).

[0070] Next, part (surface) of an extra copper film 6 deposited in the effective region, such as the device-formation-region, of the substrate W is removed, for example by chemical etching or electrolytic etching, until the copper film 6 becomes thin to a predetermined thickness, as shown in FIG. 8C, followed by cleaning (step 3). During the partial removal processing, the thickness of the remaining copper film 6 is measured and the measured thickness is fed back, whereby the removal amount of copper film 6 can be controlled in-situ. Further, according to necessity, the substrate W is subjected to annealing (heating) or infrared irradiation to grow and stabilize the metal crystals of the copper film 6 (step 4).

[0071] Next, the extra copper film 6 having the predetermined thickness, remaining on the insulating film 2 positioned in the effective region of the substrate W, and the barrier layer 5 are removed by chemical-mechanical polishing (CMP) so as to make the surface of the copper film 6, filled in the fine holes 3 and the interconnect trenches 4, substantially flush with the surface of the insulating film 2. Interconnects, which are formed of the copper film 6, as shown in FIG. 8D, are thus formed (step 5). The front and back surfaces of the substrate, having the interconnects of copper film 6, are cleaned by using a combined chemical and physical means, for example a combination of a chemical and scrubbing, and rinsed (cleaned) with pure water, followed by spin-drying (step 6). The substrate after drying is then sent to the next process.

[0072] As shown in FIG. 10, it is also possible to first remove part of the extra copper film 6 deposited in the effective region of the substrate W, such as the device-formation-region, followed by cleaning (step 2), and then remove the copper film 6 deposited in the ineffective region of the substrate W, such as the edge (bevel) portion, for example by etching, followed by cleaning and, according to necessity, also clean the back surface of the substrate (step 3).

[0073] According to this method, in advance of the CMP step and the optional step for metal crystal stabilization, such as annealing, which steps are likely to cause damage to a substrate, the copper film (metal film) 6 formed in excess in the effective region of the substrate W is made thin. This reduces a stress to interconnects 6 due to expansion/contraction difference. Further, the CMP time and the annealing time, themselves, can be minimized. Accordingly, peel-off or separation of the insulating film 2 and the copper interconnects 6 can be prevented even when a material having a low mechanical strength such as a low-k material is employed for the insulating film 2.

[0074] Though copper, a copper alloy, silver or a silver alloy is generally employed as a metal interconnect material in the present invention, usable metal interconnect materials, of course, are not limited to these metals. The present invention is particularly effective when a material having a low mechanical strength, such as a porous low-k material, is employed as a material for the insulating film (interlayer dielectric) 2.

[0075]FIG. 11 shows a substrate processing apparatus according to an embodiment of the present invention, which is suited for carrying the above-described first method. The substrate processing apparatus is comprised of a plating apparatus 100, the above-described annealing apparatus 26 shown in FIG. 5, and the above-described CMP apparatus 34 shown in FIG. 6, which are arranged in series. The plating apparatus 100 of this embodiment has a similar construction to the plating apparatus 10 shown in FIG. 4 but employs, in place of one of the two bevel etching/back surface cleaning units 20, a partial removal unit 104, for example comprised of a chemical etching unit or an electrolytic etching unit, provided with a film thickness measuring section 102 for measuring a thickness of a film. The step (step 3) of removing part (surface) of the extra copper film 6 deposited in the effective region of the substrate W, followed by cleaning, is carried out by the partial removal unit 104, and the thickness of the remaining copper film 6 is measured, during the removal processing, with a measuring device of the film thickness measuring section 102 and the measured thickness is fed back so as to control the partial removal unit 104.

[0076] Chemical agents commonly used in chemical etching include hydrogen peroxide, ozone, etc. as oxidizing agents and sulfuric acid, hydrochloric acid, hydrofluoric acid and other chelating agents as metal removal agents. It is possible to oxidize the surface of a metal film, such as the copper film 6, with ultraviolet rays. Electrolytic etching is carried out by utilizing the copper film 6 formed on the surface of the substrate W as an anode, and immersing the copper film 6 in an electrolytic solution such that the copper film 6 faces an anode disposed in the electrolytic solution and passing an electric current between the anode and the cathode, thereby oxidizing and ionizing and thereby removing the copper film 6. The measuring device of the film thickness measuring section 102 may be one that utilizes fluorescent X-rays, an eddy current, image analysis, surface reflectivity, etc.

[0077]FIG. 12 shows a substrate processing apparatus according to another embodiment of the present invention, which is suited for carrying out the above-described first method. The substrate processing apparatus is comprised of a composite apparatus 110 which combines a plating apparatus and an annealing apparatus, and the above-described CMP apparatus 34 shown in FIG. 6, which are arranged in series. The composite apparatus 110 of this embodiment has a similar construction to the composite apparatus 60 shown in FIG. 7 but employs, in place of one of the two bevel etching/back surface cleaning units 20, the partial removal unit 104 shown in FIG. 11, for example comprised of a chemical etching unit or an electrolytic etching unit, provided with the film thickness measuring section 102 for measuring a thickness of a film.

[0078]FIG. 13 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described first method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, an annealing apparatus 120, and the above-described CMP apparatus 34 shown in FIG. 6, which are arranged in series. The annealing apparatus 120 of this embodiment has a similar construction to the annealing apparatus 26 shown in FIG. 5 but additionally includes the partial removal unit 104 shown in FIG. 11, for example comprised of a chemical etching unit or an electrolytic etching unit, provided with the film thickness measuring section 102 for measuring a thickness of a film, and a cleaning unit 122 disposed between the annealing unit 30 and the partial removal unit 104.

[0079]FIG. 14 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described first method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, and a CMP apparatus 130, which are arranged in series. The CMP apparatus 130 of this embodiment has a similar construction to the CMP apparatus 34 shown in FIG. 6 but additional includes the annealing unit 30 shown in FIG. 5 and the partial removal unit 104 shown in FIG. 11, for example comprised of a chemical etching unit or an electrolytic etching unit, provided with the film thickness measuring section 102 for measuring a thickness of a film. Further, the CMP apparatus 130 employs a stage 132 and two transport robots 134, 136 as transport devices.

[0080]FIG. 15 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described first method. The substrate processing apparatus has a plurality of processing units disposed in a single apparatus frame so that a series of interconnect formation processings as shown in the flow charts of FIGS. 9 and 10 can be carried out successively in the single apparatus.

[0081] In particular, the substrate processing apparatus includes a rectangular apparatus frame 140 and transport boxes 12, detachably mounted to the apparatus frame 140, each housing substrates, e.g. substrates W having a seed layer 7, shown in FIG. 8A. Inside the apparatus frame 140 are disposed a stage 142, one plating unit 18, one bevel etching/back surface cleaning unit (ineffective region etching unit) 20, two partial removal units (effective region etching units) 104 each provided with the film thickness measuring section 102 for measuring a thickness of a film, two annealing units (crystal stabilization units) 30, two CMP units 46, one scrub cleaning unit 50, one cleaning/drying unit 52, and two transport robots 144, 146.

[0082] According to the substrate processing apparatus, substrates having a seed layer are carried one by one by the transport robot 144 from the transport box 12 into the apparatus frame 140. The substrate is then subjected to the sequential processings of: plating in the plating unit 18; removal by etching of e.g. a copper film deposited in the ineffective region of the substrate, followed by cleaning, in the bevel etching/back surface cleaning unit 20; partial removal by etching of e.g. a copper film deposited in the effective region of the substrate, followed by cleaning, in one of the two partial removal units 104; metal crystal stabilization processing in one of the two annealing units 30; and CMP in one of the two CMP units 46. The substrate is then scrub-cleaned in the scrub cleaning unit 50, and rinsed (cleaned) with pure water, followed by spin-drying, in the cleaning/drying unit 52. Thereafter, the substrate is returned by the transport robot 144 to the original position in the transport box 12.

[0083]FIG. 16 shows a flow chart of a substrate processing method according to another embodiment of the present invention (second method). According to this embodiment, as with the preceding embodiment (first method), the substrate W having the seed layer 7, shown in FIG. 8A, is first prepared. Then, as shown in FIG. 8B, copper plating of the surface of the substrate W is carried out to fill the fine holes 3 and the interconnect trenches 4 with copper and, at the same time, deposit a copper film 6 on the insulating film 2 (step 1). Thereafter, the copper film deposited in the ineffective region, such as the edge (bevel) portion, of the substrate is removed, for example by etching, followed by cleaning and, if necessary, the back surface of the substrate is also cleaned (step 2).

[0084] Next, part (surface) of an extra copper film 6 deposited in the effective region, such as the device-formation-region, of the substrate W is removed by composite electrolytic polishing until the copper film 6 becomes thin to a predetermined thickness, as shown in FIG. 8C, followed by cleaning (step 3). As with the first method, during the partial removal processing, the thickness of the remaining copper film 6 is measured and the measured thickness is fed back, whereby the removal amount of copper film 6 can be controlled in situ. Further, according to necessity, the substrate W is subjected to annealing (heating) or infrared irradiation to grow and stabilize the metal crystals of the copper film 6 (step 4).

[0085] Next, the extra copper film 6 having the predetermined thickness, remaining on the insulating film 2 positioned in the effective region of the substrate W, and the barrier layer 5 are removed by chemical-mechanical polishing (CMP) so as to make the surface of the copper film 6, filled in the fine holes 3 and the interconnect trenches 4, substantially flush with the surface of the insulating film 2. Interconnects, which are formed of the copper film 6, as shown in FIG. 8D, are thus formed (step 5). The front and back surfaces of the substrate, having the interconnects of copper film 6, are cleaned by using a combined chemical and physical means, for example a combination of a chemical and scrubbing, and rinsed (cleaned) with pure water, followed by spin-drying (step 6). The substrate after drying is then sent to the next process.

[0086] As shown in FIG. 17, it is also possible to first remove, by composite electrolytic polishing, part of the extra copper film 6 deposited in the effective region of the substrate W, such as the device-formation-region, followed by cleaning (step 2), and then remove the copper film 6 deposited in the ineffective region of the substrate W, such as the edge (bevel) portion, for example by etching, followed by cleaning and, according to necessity, also clean the back surface of the substrate (step 3).

[0087] Composite electrolytic polishing is a polishing method which comprises chelation (complexing) the surface of a metal film in an electrolytic solution to thereby make the metal film surface weak or fragile, and scrub-removing the fragile metal film by bringing the metal film into mechanical contact with a contact member. For the chelating of metal film, a chelating agent is added to the electrolytic solution. The electrolytic solution may be exemplified by an electrolytic solution containing an electrolyte, such as copper sulfate or ammonium sulfate. It is possible to add abrasive grains or a slurry to the electrolytic solution to enhance the mechanical polishing action. According to the present invention, electrolytic polishing may also be employed. Electrolytic polishing is a method which comprises interposing an ion exchanger between an electrode and a substrate, bringing the ion exchanger close to or into contact with the substrate, and applying a voltage between the electrode and the substrate while supplying pure water or ultra pure water, a liquid comprising pure water or pure water and an additive, such as a surfactant, and having an electric conductivity of not more than 500 μS/cm, preferably not more than 50 μS/cm, most preferably not more than 0.1 μS/cm, or an electrolytic solution between the electrode and the substrate between the electrode and the substrate.

[0088]FIG. 18 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described second method. The substrate processing apparatus is comprised of a plating apparatus 200, the above-described annealing apparatus 26 shown in FIG. 5, and the above-described CMP apparatus 34 shown in FIG. 6, which are arranged in series. The plating apparatus 200 of this embodiment has a similar construction to the plating apparatus 10 shown in FIG. 4 but additional includes a composite electrolytic polishing unit 210 and a cleaning/drying unit 212. The composite electrolytic polishing unit 210 includes a top ring 202, a turntable (polishing table) 204, a dresser 206 and a loader 208, and electrolytically polishes a substrate by pressing the substrate held by the top ring 202 against the polishing surface (upper surface) of the turntable 204 while moving the substrate and the turntable 204 relative to each other. The composite electrolytic polishing unit 210 is provided with the above-described film thickness measuring section 102 for measuring a thickness of a film. The step (step 3) of removing part (surface) of the extra copper film 6 deposited in the effective region of the substrate W, followed by cleaning, is carried out by the composite electrolytic polishing unit 210, and the thickness of the remaining copper film 6 is measured, during the removal processing, by the film thickness measuring section 102 and the measured thickness is fed back so as to control the composite electrolytic polishing unit 210.

[0089]FIG. 19 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described second method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, an annealing apparatus 220, and the above-described CMP apparatus 34 shown in FIG. 6, which are arranged in series. The annealing apparatus 220 of this embodiment has a similar construction to the annealing apparatus 26 shown in FIG. 5 but additionally includes the composite electrolytic polishing unit 210 shown in FIG. 18, provided with the film thickness measuring section 102 for measuring a thickness of a film, and two cleaning/drying units 212.

[0090]FIG. 20 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described second method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, and a CMP apparatus 230, which are arranged in series. The CMP apparatus 230 of this embodiment has a similar construction to the CMP apparatus 34 shown in FIG. 6 but employs, in place of one of the CMP units 46, the composite electrolytic polishing unit 210 shown in FIG. 18, provided with the film thickness measuring section 102 for measuring a thickness of a film, and additionally includes two annealing units 30. Further, the CMP apparatus 230 employs a stage 232 and two transport robots 234, 236 as transport devices.

[0091]FIG. 21 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described second method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, and a CMP apparatus 240, which are arranged in series. The CMP apparatus 240 of this embodiment has a similar construction to the CMP apparatus 230 shown in FIG. 20 but employs two CMP units 46 and three transport robots 242, 244, 246 as transport devices.

[0092]FIG. 22 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described second method. The substrate processing apparatus has a plurality of processing units disposed in a single apparatus frame so that a series of interconnect formation processings as shown in the flow charts of FIGS. 16 and 17 can be carried out successively in the single apparatus.

[0093] In particular, the substrate processing apparatus includes a rectangular apparatus frame 250 and transport boxes 12, detachably mounted to the apparatus frame 250, each housing substrates, e.g. substrates W having a seed layer 7, shown in FIG. 8A. Inside the apparatus frame 250 are disposed a stage 252, two plating units 18, one bevel etching/back surface cleaning unit (ineffective region etching unit) 20, one composite electrolytic polishing unit 210 provided with the film thickness measuring section 102, two annealing units (crystal stabilization units) 30, one CMP unit 46, two scrub cleaning units 50, one cleaning/drying unit 52, and two transport robots 254, 256.

[0094] According to the substrate processing apparatus, substrates having a seed layer are carried one by one by the transport robot 254 from the transport box 12 into the apparatus frame 250. The substrate is then subjected to the sequential processings of: plating in one of the two plating units 18; removal by etching of e.g. a copper film deposited in the ineffective region of the substrate, followed by cleaning, in the bevel etching/back surface cleaning unit 20; partial removal by etching of e.g. a copper film deposited in the effective region of the substrate, followed by cleaning, in the composite electrolytic polishing unit 210; metal crystal stabilization processing in one of the two annealing units 30; and CMP in the CMP unit 46. The substrate is then scrub-cleaned in one of the two scrub cleaning units 50, and rinsed (cleaned) with pure water, followed by spin-drying, in the cleaning/drying unit 52. Thereafter, the substrate is returned by the transport robot 254 to the original position in the transport box 12.

[0095]FIG. 23 shows a flow chart of a substrate processing method according to yet another embodiment of the present invention (third method). According to this embodiment, as with the preceding embodiments (first and second methods), the substrate W having the seed layer 7, shown in FIG. 8A, is first prepared. Then, as shown in FIG. 8B, copper plating of the surface of the substrate W is carried out to fill the fine holes 3 and the interconnect trenches 4 with copper and, at the same time, deposit a copper film 6 on the insulating film 2 (step 1). Thereafter, the copper film deposited in the ineffective region, such as the edge (bevel) portion, of the substrate W is removed, for example by etching, followed by cleaning and, if necessary, aback surface of the substrate is also cleaned (step 2).

[0096] Next, part (surface) of an extra copper film 6 deposited in the effective region, such as the device-formation-region, of the substrate W is removed by a primary CMP (first CMP) until the copper film 6 becomes thin to a predetermined thickness (step 3), as shown in FIG. 8C, followed by cleaning (step 4). As with the first and second methods, during the partial removal processing, the thickness of the remaining copper film 6 is measured and the measured thickness is fed back, whereby the removal amount of copper film 6 can be controlled in situ. Further, according to necessity, the substrate W is subjected to annealing (heating) or infrared irradiation to grow and stabilize the metal crystals of the copper film 6 (step 5). The primary CMP may be one that employs a so-called fixed abrasive method. Depending upon the purpose, instead of CMP, the partial removal of the metal film may be carried out by so-called grinding.

[0097] Next, the extra copper film 6 having the predetermined thickness, remaining on the insulating film 2 positioned in the effective region of the substrate W, and the barrier layer 5 are removed by a secondary chemical-mechanical polishing (second CMP) so as to make the surface of the copper film 6, filled in the fine holes 3 and the interconnect trenches 4, substantially flush with the surface of the insulating film 2. Interconnects, which are formed of the copper film 6, as shown in FIG. 8D, are thus formed (step 6). The front and back surfaces of the substrate, having the interconnects of copper film 6, are cleaned by using a combined chemical and physical means, for example a combination of a chemical and scrubbing, and rinsed (cleaned) with pure water, followed by spin-drying (step 7). The substrate after drying is then sent to the next process.

[0098] As shown in FIG. 24, it is also possible to carry out the secondary chemical-mechanical polishing in two steps: step 6-a of carrying out CMP (second CMP) for primarily polishing e.g. the copper film; and step 6-b of carrying out CMP (third CMP) for primarily polishing e.g. the barrier layer.

[0099]FIG. 25 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described third method. The substrate processing apparatus is comprised of a plating apparatus 300, the above-described annealing apparatus 26 shown in FIG. 5, and the above-described CMP apparatus 34 shown in FIG. 6, which are arranged in series. The plating apparatus 300 of this embodiment has a similar construction to the plating apparatus 10 shown in FIG. 4 but additional includes a first CMP unit 310 and a cleaning/drying unit 312. The first CMP unit 310 includes a top ring 302, a turntable (polishing table) 304, a dresser 306 and a loader 308, and performs CMP of a substrate by pressing the substrate held by the top ring 302 against the polishing surface (upper surface) of the turntable 304 while moving the substrate and the turntable 304 relative to each other. The first CMP unit 310 is provided with the above-described film thickness measuring section 102 for measuring a thickness of a film. The first CMP step (step 3) of removing part (surface) of the extra copper film 6 deposited in the effective region of the substrate W, is carried out by the first CMP unit 310, and the thickness of the remaining copper film 6 is measured, during the removal processing, by the film thickness measuring section 102 and the measured thickness is fed back so as to control the first CMP unit 310.

[0100]FIG. 26 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described third method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, an annealing apparatus 320, and the above-described CMP apparatus 34 shown in FIG. 6, which are arranged in series. The annealing apparatus 320 of this embodiment has a similar construction to the annealing apparatus 26 shown in FIG. 5 but additionally includes the first CMP unit 310 shown in FIG. 25, provided with the film thickness measuring section 102 for measuring a thickness of a film, and two cleaning/drying units 312.

[0101]FIG. 27 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described third method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, and a CMP apparatus 330, which are arranged in series. The CMP apparatus 330 of this embodiment has a similar construction to the CMP apparatus 34 shown in FIG. 6 but employs, in place of one of the CMP units 46, the first CMP unit 310 shown in FIG. 25, provided with the film thickness measuring section 102 for measuring a thickness of a film, and additionally includes two annealing units 30. Further, the CMP apparatus 330 employs a stage 332 and two transport robots 334, 336 as transport devices.

[0102] The remaining CMP unit 46 performs the secondary CMP (second CMP) of removing the extra copper film 6 having a predetermined thickness, remaining on the insulating film 2 positioned in the effective region of the substrate W, and the barrier layer 5 so as to make the surface of the copper film 6, filled in the fine holes 3 and the interconnect trenches 4, substantially flush with the surface of the insulating film 2.

[0103]FIG. 28 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described third method. The substrate processing apparatus is comprised of the above-described plating apparatus 10 shown in FIG. 4, and a CMP apparatus 340, which are arranged in series. The CMP apparatus 340 of this embodiment has a similar construction to the CMP apparatus 330 shown in FIG. 27 but employs two CMP units 46 so that the secondary CMP can be carried out in two steps, i.e. the step of carrying out CMP (second CMP) for primarily polishing e.g. a copper film and the step of carrying out CMP (third CMP) for primarily polishing e.g. a barrier layer, which steps are carried out separately in the two CMP units 46, and three transport robots 342, 344, 346 as transport devices.

[0104]FIG. 29 shows a substrate processing apparatus according to yet another embodiment of the present invention, which is suited for carrying out the above-described third method. The substrate processing apparatus has a plurality of processing units disposed in a single apparatus frame so that a series of interconnect formation processings as shown in the flow charts of FIGS. 23 and 24 can be carried out successively in the single apparatus.

[0105] In particular, the substrate processing apparatus includes a rectangular apparatus frame 350 and transport boxes 12, detachably mounted to the apparatus frame 350, each housing substrates, e.g. substrates W having a seed layer 7, shown in FIG. 8A. Inside the apparatus frame 350 are disposed two plating units 18, one bevel etching/back surface cleaning unit (ineffective region etching unit) 20, one first CMP unit 310, provided with the film thickness measuring section 102, for carrying out the primary CMP (the first CMP), one annealing unit (crystal stabilization units) 30, two CMP units 46 for carrying out the secondary CMP (the second CMP, or the second CMP and the third CMP), two scrub cleaning units 50, one cleaning/drying unit 52, and three transport robots 352, 354, 356.

[0106] According to the substrate processing apparatus, substrates having a seed layer are carried one by one by the transport robot 352 from the transport box 12 into the apparatus frame 350. The substrate is then subjected to the sequential processings of: plating in one of the two plating units 18; removal by etching of e.g. a copper film deposited in the ineffective region of the substrate, followed by cleaning, in the bevel etching/back surface cleaning unit 20; the primary CMP in the first CMP unit 310; metal crystal stabilization processing in the annealing unit 30; and the secondary CMP in the CMP units 46. The substrate is then scrub-cleaned in one of the two scrub cleaning units 50, and rinsed (cleaned) with pure water, followed by spin-drying, in the cleaning/drying unit 52. Thereafter, the substrate is returned by the transport robot 352 to the original position in the transport box 12.

[0107] As described hereinabove, according to the present invention, in advance of the chemical-mechanical polishing step which is likely to cause damage to a substrate, a metal film formed in excess on the substrate is made thin. This prevents peel-off or separation of an interlayer dielectric and (copper) interconnects even when a material having a low mechanical strength is employed for the interlayer dielectric, enabling a higher-yield production of a semiconductor device having a multi-layer interconnect structure of fine interconnects. Further, the present invention, through effective utilization of the existing plating apparatus, chemical-mechanical polishing apparatus, etc., enables smooth operation of a mass production factory that uses a next-generation new material.

[0108] Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims. 

What is claimed is:
 1. A substrate processing method comprising: providing a substrate having interconnect recesses formed in a surface; forming a metal film on the surface of the substrate by plating to embed the metal film in the interconnect recesses; removing an extra metal film formed in an effective region of the substrate; and flattening the surface of the substrate after the removal of the metal film by chemical-mechanical polishing.
 2. The substrate processing method according to claim 1, wherein the removal of the extra metal film formed in the effective region of the substrate is a partial removal for removing part of the extra metal film, and the thickness of the remaining metal film is measured to control the removal amount of the metal film.
 3. The substrate processing method according to claim 1, wherein the metal film is a copper, copper alloy, silver or silver alloy film.
 4. The substrate processing method according to claim 1, wherein the removal of the extra metal film formed in the effective region of the substrate is carried out by chemical etching, electrolytic etching or composite electrolytic polishing.
 5. The substrate processing method according to claim 1, wherein the removal of the extra metal film formed in the effective region of the substrate is carried out by chemical-mechanical polishing.
 6. The substrate processing method according to claim 1, further comprising: removing the metal film formed in an ineffective region of the substrate.
 7. A substrate processing method comprising: providing a substrate having interconnect recesses formed in a surface; forming a metal film on the surface of the substrate by plating to embed the metal film in the interconnect recesses; removing an extra metal film formed in an effective region of the substrate; cleaning the substrate after the removal of the metal film; subjecting the substrate after the cleaning to crystal stabilization processing to stabilize the metal crystals of the metal film; and flattening the surface of the substrate after the crystal stabilization processing by chemical-mechanical polishing.
 8. The substrate processing method according to claim 7, wherein the removal of the extra metal film formed in the effective region of the substrate is a partial removal for removing part of the extra metal film, and the thickness of the remaining metal film is measured to control the removal amount of the metal film.
 9. The substrate processing method according to claim 7, wherein the metal film is a copper, copper alloy, silver or silver alloy film.
 10. The substrate processing method according to claim 7, wherein the removal of the extra metal film formed in the effective region of the substrate is carried out by chemical etching, electrolytic etching or composite electrolytic polishing.
 11. The substrate processing method according to claim 7, wherein the removal of the extra metal film formed in the effective region of the substrate is carried out by chemical-mechanical polishing.
 12. The substrate processing method according to claim 7, further comprising: removing the metal film formed in an ineffective region of the substrate.
 13. A substrate processing apparatus comprising: a plating unit for forming a metal film on a surface of a substrate having interconnect recesses formed in a surface to embed the metal film in the interconnect recesses; a partial removal unit for removing part of an extra metal film formed in an effective region of the substrate; and a transport device for transporting the substrate between the units.
 14. The substrate processing apparatus according to claim 13, wherein the partial removal unit is a chemical etching unit, an electrolytic etching unit or a composite electrolytic polishing unit.
 15. The substrate processing apparatus according to claim 13, wherein the partial removal unit is a chemical-mechanical polishing unit.
 16. The substrate processing apparatus according to claim 13, further comprising: a removal unit for removing the metal film formed in an ineffective region of the substrate.
 17. The substrate processing apparatus according to claim 13, further comprising: a crystal stabilization unit for stabilizing the metal crystals of the metal film remaining on the substrate after the partial removal of the extra metal film in the partial removal unit.
 18. The substrate processing apparatus according to claim 13, further comprising: a cleaning unit for cleaning the substrate.
 19. The substrate processing apparatus according to claim 13, further comprising: a chemical-mechanical polishing unit for removing the extra metal film remaining on the substrate after the partial removal of the extra metal film in the partial removal unit and flattening the surface of the substrate.
 20. The substrate processing apparatus according to claim 13, further comprising: a film thickness measuring section for measuring the thickness of the metal film remaining on the substrate after the partial removal of the extra metal film in the partial removal unit, and controlling the partial removal unit based on the results of the measuring. 